SAINT-ETIENNE A prosecutor has ordered a new autopsy on an inmate whose death triggered three nights of street violence.

Angry youths trashed cars and threw stones at police and firefighters during the unrest in Firminy, outside Saint-Etienne in central France. Police hit back with tear gas.

Prosecutor Jacques Pin ordered a second autopsy on the body of Mohamed Benmouna, 21, who police said tried to hang himself in his jail cell on Tuesday and who died in a hospital the next day.

Family members and enraged youths believe the death of Benmouna, under investigation for extortion, was caused by police.

In announcing the second autopsy, the prosecutor said he "has taken a maximum of precautions and honoured the request of the family".

"The conclusions will be compared to those of the first autopsy, which excluded any trace of violence," he said.

The prosecutor added that "the young man died of cardiac arrest by suffocation" after hanging himself from his cell's plasterboard wall.

Interior Minister Brice Hortefeux also said it was a suicide. He said: "A young man was detained as part of a probe into extortion. He was put in detention, and during his detention he wanted to commit suicide and unfortunately, he did so."

Benmouna's parents, while calling for calm, have filed a judicial complaint asking for a full investigation.

Some 60 youths first went on a rampage on Tuesday night, burning 30 cars and hurling stones at police in three nearby neighbourhoods. Police reinforced patrols but failed to halt the unrest.

Yesterday 10 cars and seven stores in a shopping centre were torched, said a fire department spokesman.

Police reported that six young people had been detained.

Officials are alert to violence between youths and police in suburbs surrounding large French cities. In 2005 unrest spread across the country, triggered by the deaths of two teens trying to escape police in Paris. Those riots hit housing projects where residents often have roots in France's former African colonies. Youths exploded in anger over discrimination and exclusion from mainstream French society. - AP